Circuit breaker with improved contact structure



Oct. 5, R. E. FRINK CIRCUIT BREAKER WITH IMPROVED CONTACT STRUCTUREOriginal Filed Dec. 13, 1957 3 Sheets-Sheet l Russell E. Frink Wm MATTORNEY Oct. 5, 1965 R. E. FRINK 3,210,505

CIRCUIT BREAKER WITH IMPROVED CONTACT STRUCTURE Original Filed Dec. 13,1957 3 Sheets-Sheet 2 R. E. FRINK 3,210,506 CIRCUIT BREAKER WITHIMPROVED CONTACT STRUCTURE 3 Sheets-Sheet 3 Original Filed Dec. 15, 19575 m C\\mum 5 III United States Patent 3,210,506 CIRCUIT BREAKER WITHIMPROVED CONTACT STRUCTURE Russell E. Frink, Forest Hills, Pa., assignorto Westinghouse Electric Corporation, East Pittsburgh, Pa., acorporation of Pennsylvania Original application Dec. 13, 1957, Ser. No.702,576, now Patent No. 2,993,105, dated July 18, 1961. Divided and thisapplication Sept. 20, 1960, Ser. No. 57,320 11 Claims. (Cl. 200-146)This invention relates to contact structure and more particularly tocontact structures for circuit breakers.

This is a division of the application of Russell E. Frink titled,Circuit Breaker, Serial No. 702,576, filed December 13, 1957, now PatentNo. 2,993,105.

An object of the invention is to provide a circuit breaker embodying animproved contact structure that is compact and has high momentary andcontinuous current-carrying capacity.

Another object of the invention is to provide a circuit breakerembodying an improved contact structure having high interrupting andcurrent-carrying capacities.

Another object of the invention is to provide a circuit breakerembodying an improved contact structure having main, secondary andarcing contacts for heavy duty and which are so compact that all of theseparating contacts may be located within an arc chute to prevent thearc from restriking outside of the arc chute where it will not beextinguished.

The invention has been illustrated by showing a contact structure andmounting arrangement therefor, designed for a magnetic air circuitbreaker having a momentary current rating of 100,000 amperes, acontinuous current-carrying rating of 3,000 amperes, and an interruptingrating of 50,000 amperes, but the invention may be used with advantagein circuit breakers of other ratings. In such heavy duty circuitbreakers, it has been found that: (1) There should be main, secondaryand arcing contacts in order to keep the main contacts in good conditionto conduct the heavy currents, (2) The physical size of the contactassembly in the direction along the length of the moving contact armshould be as small as possible compared to the length of the movingcontact arm to provide a maximum rate of contact separation, and to keepthe separating main contacts from being significantly closer together atany point during their separation than are the separating arcingcontacts, so that there will be little chance that the arc will restrikeacross the gap between the main contacts rather than to remain on thearcing contacts, and (3) The contact assembly should be so small thatthe main, secondary and arcing contacts may all be positioned up withinthe arc chute of the circuit breaker, so that if the arc should restrikebetween any of the contacts, due to the switching of capacitor banks orto abnormal circuit conditions, the restrikes will be confined to thearc chute where the arc will be extinguished by the arc-extinguishingstructure provided. Accordingly, other objects of the invention are toprovide for these features.

Another object of the invention is to mount the contact structure oninsulated terminal studs having a compact and efiicient arrangement forconducting the heavy current to the contacts.

Other objects and advantages of the invention will 3,210,506 PatentedOct. 5, 1965 be pointed out in the following description and illustratedin the accompanying drawings, which disclose, by way of example, theprinciple of the invention and the best mode, which has beencontemplated, of applying that principle.

In said drawings:

FIG. 1 is a side elevational View, partly in section of a circuitbreaker embodying the principles of the invention;

FIG. 2 is an enlarged elevational view, partly in section, showing theimproved contact structure in the closedcontact position;

FIG. 3 is a horizontal sectional view taken through the contactstructure on line III-III of FIG. 2;

FIG. 4 is a front elevational view of the stationary contact structure;

FIG. 5 is an elevational sectional View through the the stationarycontact structure taken on lines VV of FIG. 4;

FIG. 6 is a side elevational view showing one of the terminal studshaving contact fingers thereon for plugging the breaker into a cubicle;

FIG. 7 is a vertical sectional view taken through one of the terminalstuds;

FIG. 8 is an elevational sectional view taken on line VIIIVIII of FIG. 1and showing the terminal studs and the mounting means therefor; and

FIG. 9 is a perspective view illustrating parts of the pressureequalizing means of this invention.

The invention is illustrated as applied to a circuit breaker of thegeneral type disclosed in Patent No. 2,717,292, issued September 6, 1955to Russel E. Frink and Paul Olson and assigned to the assignee of thepresent invention.

The circuit breaker comprises generally a set of is of the roll-out typeand is mounted on a wheeled truck to facilitate movement of the breakerinto and out of a cubicle in order to connect and disconnect the breakerin an electrical circuit.

Referring to FIG. 1 of the drawings, the circuit breaker is of the threepole type (only one pole being shown) and is mounted in a rigid framecomprising spaced triangular side plates 11 (only one being shown)rigidly secured together by cross members 13, 15, 17 and 19 to form arigid frame. The frame, together with the circuit breaker, is mounted onwheels 20 to facilitate rolling the breaker into and out of a cubicle.

The circuit breaker comprises generally a set of separable contact means21 for each pole, a common operating mechanism 23, a trip device 25 andclosing means 27.

The contact structure comprises generally a stationary contact assembly29 rigidly mounted on the inner end of an upper terminal stud 31 ofhollow rectangular shape.

The terminal stud 31 is encased in insulating material 33 and is rigidlyclamped by means of bolts 35 between supporting aluminum cross bars 37which extend across the three poles of the breaker and are secured bymeans of bolts 39 to the spaced side plates 11 of the frame. The contactstructure also includes a movable switch arm 41 pivotally supported on acasting 43 rigidly secured to the inner end of a lower terminal stud 45which also is of hollow rectangular shape. The lower terminal stud 45(FIGS. 7 and 8) is surrounded by insulating material 47 and is rigidlyclamped between supporting cross bars 49 by means of bolts 51, the crossbars 49 extending across all these poles and are secured to the sideplates 11 by bolts 53 (FIG. 8).

The terminal studs 31 and 45 are made hollow to provide greaterconductivity by reduction of the skin effect. A substantial reduction inthe overall height of the breaker is effected by making the terminalstuds rectangular rather than round, and supporting them between thecross bars 37 and 49 eliminates metal flanges on the bushings.

The movable switch arm consists of two pairs of arms 55 and 57 (FIG. 3)bolted together at their upper ends by means of bolts 58 (FIG. 2) with amovable contact member 59 between them. The lower ends of the pairs ofswitch arms 55 and 57 are spaced apart as shown in FIG. 3 and each pairis pivotally supported by means of pins 61 (only one being shown)supported in projection 63 (FIGS. 1 and 2) on the casting 43. Springwashers 65 disposed on the outer sides of each pair of switch arms 55and 57 provide good contact pressure between the switch arms and theprojections 63. The movable switch member 59 has an arcing contact 67(FIG. 2) rigidly secured to the upper end thereof and a secondarycontact 69 rigidly secured thereto adjacent the lower end thereof. Arcresisting main movable contact strips 71 are rigidly secured to theopposite edges of the contact member 59 for engagement with mainstationary contact fingers 73.

The stationary'contact assembly 29 is mounted on a conducting block 75rigidly secured to the inner end of the upper terminal stud 31 andcomprises a plurality of stationary contact fingers 73 and a pluralityof stationary contact fingers 77 which at their upper ends havestationary arcing contacts 79 rigidly mounted thereon for cooperatingwith the movable arcing contact 67. Stationary secondary contacts 81 aremounted on the lower ends of the fingers 77. Each of the main stationarycontact fingers 73 has an arc resisting contact 83 rigidly securedthereto for cooperating with the movable main contact strips 71. Themain stationary contact fingers 73 are biased inwardly to providepressure by springs 85 surrounding rods 87 which extend horizontallythrough openings in the contact fingers 73 and through an opening in acontact support member 89 rigidly secured to the block 75. The springs85 are compressed between the contact fingers 73 and washers 91 whichare retained in place by nuts 93 threaded onto the outer ends of therods 87. The springs 85 press rounded inner ends of the main contactfingers against the contact support member 89 to provide good electricalcontact. Each of the contact fingers 73 is provided with an inwardlyprojecting portion 95 which extends into recesses 97 in the contactsupport members 89 to prevent longitudinal movement of the fingers. Asis shown in FIGURE 3, the beveled contact surface of the contacts 71, 83engage along two planes that converge in the direction toward thesupport member 89. Thus, the contacts 71, 83 cooperate to form a wedgingcontact structure with the contacts 71 wedging the contacts 83 apart inthe closed position of the contact structure. Each pair of contactfingers 73 comprises two elongated contact members supported incantilever support on the support member 89 to provide generallyparallel conducting paths between the contacts 71, 83 and the supportmember 89. The magnetic forces generated by current in the generallyparallel conducting paths attract the members 73 together to off-setbelow-off forces at the contacts 71, 83.

The main contact fingers 73 are positioned in two vertical opposed rows,with half of the fingers in each row. The length of the rows runs, inthe same general direction as the length of the moving switch arm and inthe same direction as the height, rather than the width of the arcchute. This keeps the width of the stationary contact assembly to aminimum and makes it possible to position the main contacts within thearc chute, in spite of the large number of main contact members requiredfor the 4. heavy currents. In the specific embodiment shown for thepurposes of illustration, there are ten main contact members 73, and ifthese ten main contacts had been put in a single horizontal row,generally perpendicular to the length of the moving switch arm, thewidth of the assembly would be too great to be positioned in the portionof the arc chute which is lined with arc-resisting material and which iseffective to act upon the arc to extinguish it.

The contact fingers 77 are pivotally and slidably sup ported at theirlower ends by a rod 103 having its ends supported in slots 105 (FIG. 2)in forwardly extending projections 107 of a cage 99. The contact fingers77 are provided with openings 109 which are larger than the diameter ofthe rod 103 to provide for individual movement of the contact fingers.Flexible conductors 111 secured by means of bolts 113 to the contactfingers 77 and by bolts 115 to the contact support member 89electrically connect the fingers 77 through the member 89 and the block75 to the terminal stud 31.

The upper ends of the contact fingers 77 are controlled in theirmovement by a rod 117 (FIGS. 2, 4. and 5) extending through openings 119in the fingers. The openings 119 are somewhat larger than the diameterof the rod 117 to provide for individual movement of the fingers 77. Theends of the rod 117 engage in enlarged slots 121 (FIG. 2) in projections123 of the retaining cage 99 and the rod 117 is retained in position bysmall retaining plates 125 secured to opposite sides of the projection123 by means of bolts 127 and engagingthe ends of the rod 117.

The lower ends of the contact fingers 77 are individually biased forsecondary contact pressure by means of springs 129 compressed betweenspring seats in the retaining cage 99 and spring guide 131 on thecontact fingers. The upper ends of the contact fingers 77 are biased bya pair of springs 133 (FIG. 5) compressed between a spring seat on aportion 135 of the retaining cage 99 and a movable spring seat 137. Aninsulating member 138 is disposed between the springs 133 and the springseat 137. A pressure equalizing member 139 (FIGS. 4, S and 9) in theshape of an equilateral triangle is provided with a projection 141 oneach of its apices which engage in notches 143 in the contact fingers 77The equalizer 139 is also provided with a socket (FIG. 9) at itsgeometric center which is engaged by a projection on ball portion 142 onthe movable spring seat 137. The upper projection 141 on the pressureequalizer 139 engages a notch 143 (FIG. 5) in the center one of thecontact fingers 77 and the lower projections engage the notches 143 forthe outer fingers 77 thus equalizing the pressure of the springs 133 onall three of the fingers 77. Each of the members 137 and 139 comprises abody of rigid material such as bronze. The ball-and-socket or universaltype connection 140, 142 permits a wobbling or universal type motion ofthe pressure equalizer 139 relative to the spring seat 137 to therebyprovide that the pressure or force of the springs 133 acting on each ofthe three contact fingers 77 will be generally equal to the pressure orforce of the springs 133 acting on each of the other two of the threecontact fingers 77.

The use of the spring-biased main, secondary and arcing contacts, as at73, 81 and 79, all'on the stationary contact assembly, has the advantagethat the moving contact assembly is greatly simplified in that one rigidstructure includes the moving main, secondary and arcing contacts, whichmay all be brazed to a common contact member. Thus, the main contactsurfaces 71, the secondary contact surfaces 69 and arcing contactsurfaces 67 are rigid with each other and with the moving switch arm 57,and there is no need on the moving contact assembly for any biasingsprings, any sliding contact surfaces, or any flexible currentconductors.

Each of the terminal studs 31 and 45 are provided with a plurality ofpairs of spring biased contact fingers 145 as shown in FIG. 6, forengaging fixed contacts 147 hav ing flat side surfaces to connect thebreaker in an electrical circuit.

The use of the rectangular terminal studs 31 and 45 has the advantagethat each of the two opposed parallel sides of the rectangle maydirectly support a plurality of pairs of the opposed contact fingers 145in a straight row without the use of any intermediate member in thecurrent path. This is true of both of the terminal studs 31 and 45. Thiskeeps the number of joints in the current path to a minimum andfacilitates the carrying of heavy currents. The outer contact finger 145of each pair in the row directly engages at its inner end with the outersurface of one side of the hollow rectangle and the inner finger of eachpair in each row similarly engages the inner surface of one side of thehollow rectangle.

The movable switch arm 41 (FIG. 1) for operating the movable contacts(there being a switch arm 41 for each pole of the breaker) isoperatively connected by means of an insulating operating rod 149 to theoperating mechanism 23. The upper ends of the operating rods 149 arepivotally connected by means of pivot pins 151 to the correspondingswitch arms 41, and the lower ends of the operating rods are connectedby suitable means to an angular crossbar 153 which is common to all ofthe poles of the breaker.

The specific structure of the operating mechanism, trip mechanism andthe closing means shown are fully disclosed in Patent No. 2,515,994,issued July 18, 1950, to Joseph D. Findley, Alvin W. Ogg and Fritz E.Florschutz and assigned to the assignee of the present invention, forwhich reason only a brief description of these mechanisms is givenherein.

The crossbar 153 is pivotally connected at its ends by pivot pins 155(only one being shown) to an operating lever 161 which is pivotallymounted on a shaft 167 supported in the side members of a generallyU-shaped frame 169. The frame 169 is supported on the cross members 13,17 and 19 and is shown partly broken away more clearly to Show theoperating mechanism.

In addition to the operating lever 161, the operating mechanism consistsof a closing lever 171 also pivotally mounted on the shaft 167 andconnected by means of a link 173 to the moving armature 175 of theclosing solenoid 27. The operating lever 161 and the closing lever 171are connected by means of an underset thrust-transmitting togglecomprising toggle links 177 and 179 which are pivotally connectedtogether by a knee pivot pin 181. The toggle link 177 is pivotallyconnected to the operating lever 161 and the toggle link 174 ispivotally connected to the closing lever 177.

The closing lever 171 is held in the closed position by a spring biasedlatch 183 which normally engages a roller 185 on the closing lever 171and holds the latter in the position shown.

The toggle 177 and 179 is releasably held in a slightly undersetposition by a latch member 187 mounted on the shaft 167 for rotarymovement relative thereto. A link 189 connects the latch member 187 tothe knee of the toggle 177-179 and the latch member is normallyreleasably held in latching position by the latching and trippingmechanisms 25 thus holding the toggle 177-179 in thrust-transmittingposition. The latch member 187 is held in latching position by anintermediate slip-ofi? latch 191 which, in turn, is held in latchingposition by a trigger latch 193. A tripping electromagnet 195 isprovided to operate the latch mechanism and effect release of theoperating mechanism and opening of the breaker.

When an overload current occurs, the tripping electromagnet 195 isenergized and operates the latch mechanism to effect release of thelatch member 187. Upon release of the latch member 187, the toggle177-179 collapses permitting clockwise rotation of the operating lever161 and opening movement of the switch arms 41 for .the several poles ofthe breaker.

During the opening operation, the toggle 177-179 automatically is resetto thrust-transmitting position and the latch member 187 is reset andrelatched. This is effected by spring means 197 which is connected undertension between the armature of the closing solenoid 27 and the closinglever 171 at a point near the shaft 167. When the toggle 177-179collapses during an opening operation, a roller 199 on the toggle link179 engages a nose 201 on the latch 183 and moves the latch to disengageit from the roller 185. This releases the closing lever 171 whereuponthe spring 197 moves the armature 175 and, through the link 173connecting the armature to the closing lever 171, moves the latterclockwise. This movement extends the toggle 177-179 to its thrusttransmitting position and, through the link 189, rotates the latchmember 187 clockwise to its latching position, permitting resetting ofthe latch mechanism. Thereafter, the circuit breaker is closed byenergization of the closing solenoid 27 from any suitable source. Whenenergized, the solenoid attracts its armature 175 and, through the link173, rotates the closing lever 171 counterclockwise. Since, at thistime, the toggle 177179 is held in thrust transmitting position, themovement of the closing lever is transmitted therethrough and actuatesthe operating lever 161 and the rods 149 to close the contact means forthe several poles of the breaker. As the mechanism reaches the closedposition, the latch 183 re-engages the roller and restrains the breakermechanism in the closed contact position.

The separating contacts are all disposed well within anarc-extinguishing structure indicated generally at 205 (FIGS. 1 and 2)so that when the contacts separate and the moving contact means moves tothe full open position, the are drawn between the separating arcingcontacts is drawn into the arc-extinguishing structure where it isquickly extinguished. The are extinguisher 205 may be of the generaltype shown in Dickinson and Frink Patent No. 2,442,199, issued May 25,1948 or in Frink Patent No. 2,769,065, issued October 30, 1956. As seenin FIG. 1, the arc-extinguisher 205 is pivotally mounted by means ofspaced brackets 207 (only one being shown) secured to the upper crossbar37 by the bolts 35 which clamp the upper terminal stud in position.

The invention provides an improved contact structure which increases themomentary and continuous currentcarrying capacity in a small, compactcontact arrangement which permits placing the entire separating contactstructure inside the arc chute, hence, any restriking of the arc willoccur between the contact structure and will be confined within thearc-extinguisher.

While the invention has been disclosed in accordance with the provisionsof patent statutes, it is to be understood that various changes in thestructural details and arrangement of parts may be made Withoutdeparting from the spirit of the invention.

I claim as my invention:

1. A circuit breaker comprising a first contact structure and a secondcontact structure, means for effecting relative movement between saidcontact structures to operate said contact structures between open andclosed positions, said first contact structure comprising a conductingsupport structure, two main contact members mounted on said conductingsupport structure in a spaced relationship, oppositely disposed maincontact surfaces one on each of said two main contact members,intermediate contact means supported on said support structure betweensaid main contact members, said intermediate contact means comprising asecondary contact and an arcing contact, secondary contact means on saidsecond contact structure cooperating with said secondary contacts,arcing contact means on said second contact structure cooperating withsaid arcing contact, spaced main contact means on said second contactstructure cooperating with said oppositely disposed main contactsurfaces, said spaced main contact means and said oppositely disposedmain contact surfaces comprising a cooperating wedging contact structurewith 7 the engaging surfaces between said spaced main contact means andsaid oppositely disposed main contact surfaces engaging generally alongtwo planes that converge in the direction toward said conducting supportstructure.

2. A circuit breaker comprising a first contact structure and a secondcontact structure, means for effecting relative movement between saidcontact structures to operate said contact structures between open andclosed positions, said first contact structure comprising a firstsupport means, two spaced rows of main contact members mounted on saidfirst support means for resilient movement, a first main contact surfaceon each of said main contact members, an intermediate contact structureresiliently supported on said first support means, said intermediatecontact structure comprising a secondary contact and an arcing contact,said secondary and arcing contacts being disposed in a line extendingbetween said rows of main contact members which line extends generallyin the direction of each of said rows, said second contact structurecomprising spaced second main contact surfaces, a secondary contactsurface and an arcing contact surface, in the closed position of saidcontact structures said secondary contact surface engaging saidsecondary contact, said arcing contact surface engaging said arcingcontact, and said second main contact surfaces engaging said first maincontact surfaces with said second main contact surfaces being disposedbetween the first main contact surfaces of said spaced rows of maincontact members to bias the first main contact surfaces apart.

3. A circuit breaker comprising a first contact structure and a secondcontact structure, means for effecting relative movement between saidcontact structures to operate said contact structures betweeen open andclosed positions, said first contact structure comprising a supportstructure comprising a conducting support member, a plurality of pairsof main contact members mounted on said conducting support member forresilient movement, each of said pairs comprising two spaced maincontact members mounted on said conducting support member in cantileversupport and extending out beyond said support member in a generallyparallel relationship in the direction toward said second contactstructure, each of said main contact members having a main contactsurface thereon disposed in a position beyond said support member, eachof said pairs of main contact members comprising generally parallelconducting paths between the main contact surfaces thereof and saidconducting support member, intermediate contact means supported on saidsupport structure between the spaced main contact members of said pairsof main contact members, said intermediate contact means comprising asecondary contact and an arcing contact, secondary contact means on saidsecond contact structure cooperating with said secondary contact, arcingcontact means on said second contact structure cooperating with saidarcing contact, main contact means on said second contact structurecooperating with said main contact surfaces, in the closed position ofsaid contacts said main contact means engaging said spaced main contactsurfaces and being disposed between said spaced main contact surfaces ofsaid spaced pairs of main contact members to bias said spaced maincontact surfaces apart.

4. A circuit breaker comprising a first contact structure and a secondcontact structure, means for effecting relative movement between saidcontact structures to operate said contact structures between open andclosed positions, said first contact structure comprising a supportstructure comprising a conducting support member, two main contactmembers resiliently mounted on said conducting support member in aspaced relationship, each of said main contact members being mounted onsaid conducting support member in cantilever support, each of said maincontact members extending beyond said support member toward said secondcontact structure and having a beveled main contact surface in proximityto the outer end thereof, intermediate contact means supported on saidsupport structure between said main contact members, said intermediatecontact means comprising a secondary contact and an arcing contact,secondary contact means on said second contact structure cooperatingwith said secondary contact, arcing contact means on said second contactstructure cooperating with said arcing contact, beveled main contactmeans on opposite sides of said second contact structure cooperatingwith said beveled main contact surfaces, said beveled main contact meansand said beveled main contact surfaces comprising a cooperating wedgingcontact structure whereby in the closed position of said contacts saidbeveled main contact means engage said beveled main contact surfaceswith a wedging action wedging said beveled main contact surfaces apart.

5. A circuit breaker comprising a first contact structure and a secondcontact structure, means for effecting relative movement between saidcontact structures to operate said contact structures between open andclosed positions, said first contact structure comprising a supportstructure comprising a first conducting support member, a first row ofmain contact members resiliently supported on one side of said firstsupport member, a second row of main contact members resilientlysupported on the side of said first support member that is opposite saidone side, intermediate contact means supported on said support structurebetween said first and second rows of main contact members, saidintermediate contact means comprising a secondary contact resilientlysupported on said first support member and an arcing contact resilientlysupported on said first support member, said second contact structurecomprising a second conducting support member, secondary contact meansrigidly supported on said second support member for cooperating withsaid secondary contact, arcing contact means rigidly supported on saidsecond support member for cooperating with said arcing contact, firstmain contact means rigidly supported on one side of said second supportmember for cooperating with said first row of main contact members, andsecond main contact means rigidly supported on the other side of saidsecond support member for cooperating with said second row of maincontact members, in the closed position of said first and second contactstructures the points of engagement between said first row of maincontact members and said first main contact means being disposedgenerally in a first plane that is slanted relative to the direction ofrelative movement between said contact structures and the points ofengagement between said second row of main contact members and saidsecond main contact means being disposed generally in a second planethat is slanted relative to the direction of relative movement betweensaid contact structures, said first and second planes converging in thedirection toward said support structure whereby in the closed positionof said first and second contact structures said first and secondcontact means engages said first and second rows of main contact memberswith a wedging action.

6. A circuit breaker comprising a stationary contact structure and amovable contact structure movable into and out of engagement with saidstationary contact structure, said stationary contact structurecomprising support means, a plurality of pairs of elongated main contactfingers resiliently mounted on said support means, said elongated maincontact fingers comprising two vertical rows of horizontally disposedcontact fingers, said two rows being spaced whereby each of said pairscomprises one contact finger from each of said rows, each of said maincontact fingers having a main contact surface thereon, a plurality ofintermediate contact structures supported on said support means betweensaid rows of contact fingers in a side-by-side relationship, each ofsaid intermediate contact structures comprising a secondary contact andan arcing contact, said movable contact structure comprising secondarycontact means for cooperating with said secondary contacts, arcingcontact means for cooperating with said arcing contacts, main contactmeans for cooperating with said main contact surfaces, and in the closedposition of said contact structures the points of engagement betweensaid main contact means and said main contact surfaces being disposedgenerally in opposite planes that converge in the direction generallytoward said stationary contact structure.

7. In a circuit breaker, a stationary contact structure comprising fixedsupport means, a plurality of pairs of elongated main contact membersdisposed horizontally on opposite sides of said fixed support means andbiased inwardly toward said fixed support means, a contact surface ateach end of each of said main contact members with the contact surfacesat one end engaging said fixed support means and the contact surfaces atthe other end being beveled, a plurality of unitary elongatedintermediate contact members mounted on said fixed support means anddisposed vertically between said main contact members and biased awayfrom said fixed support means, each of said intermediate contact membershaving a secondary contact and an arcing contact thereon, movablecontact means cooperating with said stationary contact structure,beveled contact surfaces on opposite sides of said movable contact meanscooperating with said beveled contact surfaces on said main contactmembers, secondary contact means on said movable contact meanscooperating with said secondary contacts, and arcing contact means onsaid movable contact means cooperating with said arcing contacts.

'8. A circuit breaker comprising -a first contact structure and a secondcontact structure cooperable with said first contact structure to openand close an electric circuit, said first contact strucure comprisingsupport means comprising a first support member of conducting material,a plurality of pairs of main contact members disposed on said firstsupport member such that the two main contact members of each pair aredisposed on opposite sides of said first support member, meanssupporting said main contact members on said first support member andcomprising a rod for each of said pairs of main contact members whichrod passes through an opening in each of the main contact members of theassociated pair and through an opening in said first support member, twosprings for each of said rods and disposed one each on each of the twoopposite ends of said rods, said springs biasing said main contactmembers inwardly toward said first support member, each of said maincontact members extending out past said first support member andcomprising a main contact surface at the outer end thereof, a pluralityof intermediate contact structures mounted on said support means anddisposed between the oppositely disposed main contact members of saidpairs of main contact members, each of said intermediate contactstructures comprising a secondary contact and an arcing contact, saidsecond contact structure comprising a second support member ofconducting material, main contact surfaces disposed on opposite sides ofsaid second support member for cooperating with said main contactsurfaces on said main contact members, secondary contact means on saidsecond support member for cooperating with said plurality of secondarycontacts, arcing contact means on said second support member forcooperating with said plurality of arcing contacts, said first contactstructure and said second contact structure being constructed forrelative movement into closed and opened positions, and in the closedposition of said contact structures said main contact surfaces on saidsecond support member being disposed between the oppositely disposedmain contact surface-s of said pairs of main contact members.

9. A circuit breaker comprising, in combination, a stationary contactstructure and a movable contact structure movable into and out ofengagement with said stationary contact structure, said stationarycontact structure comprising support means comprising a stationarysupport member of conducting material, a plurality of pairs of elongatedmain contact members disposed horizontally in two vertical rows on saidstationary support member, means supporting said main contact members onsaid stationary support member, a first spring means biasing said maincont-act members inwardly toward said first support member, saidelongated main contact members extending out beyond said first supportmember, each of said main contact members comprising a beveled maincontact surface at the outer end thereof, a plurality of elongatedunitary intermediate contact members supported vertically in aside-by-side relationship between said main contact members, each ofsaid unitary intermediate contact members having a secondary contact inproximity to the bottom thereof and an arcing contact in proximity tothe top thereof, a second spring means biasing the tops of saidintermediate contact members away from said support member and providingan individual bias against the top of each of the intermediate contactmembers, a third spring means biasing the bottoms of said intermediatecontact members away from said first support member and providing aseparate bias against the bottom of each of said intermediate contactmembers, means limiting movement of said intermediate contact membersaway from said first support member, said movable contact structurecomprising a movable support member of conducting material, beveled maincontact surfaces on opposite sides of said movable support member forcooperating with said beveled main contact surfaces of said main contactmembers, secondary contact means on said movable support member forcooperating with said plurality of secondary cont-acts, arcing contactmeans on said movable support member for cooperating with said pluralityof arcing contacts, and in the closed position of said contactstructures said beveled main contact structures on said movable supportmember engaging said beveled main contact surfaces on said main contactmembers with an orientation wedg ing said rows of main contact membersapart.

10. In a circuit breaker, a stationary contact structure comprisingsupport means, a plurality of pairs of main stationary contact membersdisposed on opposite sides of said support means and pivotally supportedat one end on said support means, separate means biasing each of saidpairs of main stationary contact members toward said support means, aplurality of intermediate stationary contact members disposed betweensaid pairs of main stationary contact members, each of said intermediatecontact members including a secondary contact and an arcing contact,means supporting one end of said intermediate contact members on saidsupport means for pivotal and sliding movement toward and away from saidsupport means, biasing means biasing the pivoted ends of saidintermediate contact members for sliding movement away from said supportmeans, separate means biasing the other ends of said intermediatecontact members for pivotal movement away from said support means, andmovable contact means cooperating with said stationary contactstructure.

11. In a circuit breaker, a frame, a stationary contact structurecomprising support means secured to said frame, a plurality of pairs ofmain stationary contact members disposed on opposite sides of saidsupport means and pivotally supported at one end on said support means,separate means biasing each of said pairs of main stationary contactmembers toward said support means, a plurality of intermediatestationary contact members disposed between said pairs of mainstationary contact members, each of said intermediate contact memberscomprising a secondary contact and an arcing contact, means supportingone end of said intermediate contact members on said support means forpivotal and sliding movement toward and away from said support means,individual biasing means biasing the pivoted ends of said intermediatecontact members for sliding movement away from said support means,separate means common to said plurality of intermediate contact membersbiasing the other ends of said intermediate contact members for pivotalmovement away from said support means, and movable contact meanscooperating with said stationary contact structure.

References Cited by the Examiner UNITED STATES PATENTS 7 1,843,804 2/32Christie 200166 1,978,246 10/34 Bauerschmidt 200-166 2,324,891 7/43Thumin 200146 2,426,387 8/47 Caswell 200146 2,646,482 7/53 Wood et al.200147 12 7/53 Miller 200147 5/55 Jansson 200166 9/55 Frink et a1 2001661/56 Curtis 200166 8/56 Ulrich 200146 8/58 Frink 200146 6/59 Ramrath200166 FOREIGN PATENTS 6/31 Germany.

BERNARD A. GILHEANY, Primary Examiner.

MAX L. LEVY, Examiner.

1. A CIRCUIT BREAKER COMPRISING A FIRST CONTACT STRUCTURE AND A SECONDCONTACT STRUCTURE, MEANS FOR EFFECTING RELATIVE MOVEMENT BETWEEN SAIDCONTACT STRUCTURES TO OPERATE SAID CONTACT STRUCTURES BETWEEN OPEN ANDCLOSED POSITIONS, SAID FIRST CONTACT STRUCTURE COMPRISING A CONDUCTINGSUPPORT STRUCTURE, TWO MAIN CONTACT MEMBERS MOUNTED ON SAID CONDUCTINGSUPPORT STRUCTURE IN A SPACED RELATIONSHIP, OPPOSITELY DISPOSED MAINCONTACT SURFACES ONE ON EACH OF SAID TWO MAIN CONTACT MEMBERS,INTERMEDIATE CONTACT MEANS SUPPORTED ON SAID SUPPORT STRUCTURE BETWEENSAID MAIN CONTACT MEMBERS, SAID INTERMEDIATE CONTACT MEANS COMPRISING ASECONDARY CONTACT AND AN ARCING CONTACT, SECONDARY CONTACT MEANS ON SAIDSECOND CONTACT STRUCTURE COOPERATING WITH SAID SECONDARY CONTACTS,ARCING CONTACT MEANS ON SAID SECOND CONTACT STRUCTURE COOPERATING WITHSAID ARCING CONTACT, SPACED MAIN CONTACT MEANS ON SAID SECOND CONTACTSTRUCTURE COOPERATING WITH SAID OPPOSITELY DISPOSED MAIN CONTACTSURFACES, SAID SPACED MAIN CONTACT MEANS AND SAID OPPOSITELY DISPOSEDMAIN CONTACT SURFACES COMPRISING A COOPERATING WEDGING CONTACT STRUCTUREWITH THE ENGAGING SURFACES BETWEEN SAID SPACED MAIN CONTACT MEANS ANDSAID OPPOSITELY DISPOSED MAIN CONTACT SURFACES ENGAGING GENERALLY ALONGTWO PLANES THAT CONVERGE IN THE DIRECTION TOWARD SAID CONDUCTING SUPPORTSTRUCTURE.